GFCI that cannot be reset until wired correctly on line side and power is applied

ABSTRACT

An apparatus and method for preventing the miswiring of a protection device. The protection device includes line terminals and load terminals. The protection device further includes a latching mechanism, adapted to move between a closed state which establishes electrical contact between said line and load terminals, and an open state which prevents electrical contact between said line and load terminals; and an initial reset prevention mechanism, adapted to prevent said latching mechanism from being set in said closed state until power is applied to said line terminals.

PRIORITY CLAIM

This application is a continuation of application Ser. No. 12/385,394,filed Apr. 7, 2009 now U.S. Pat. No. 7,889,465, which is a continuationof application Ser. No. 11/655,255, now U.S. Pat. No. 7,538,994, filedJan. 9, 2007, which is a continuation of application Ser. No.10/434,101, now U.S. Pat. No. 7,184,250, filed May 9, 2003, which claimsbenefit from U.S. Provisional Patent Application Ser. No. 60/378,647,filed on May 9, 2002 entitled “GFCI With Reversible Line/Load WiringCapability”, the entire contents of which are incorporated herein byreference.

CROSS REFERENCE TO RELATED APPLICATIONS

Related subject matter is disclosed in U.S. patent application Ser. No.10/032,064, filed on Dec. 31, 2001 entitled “Ground Fault CircuitInterrupter (GFCI) With A Secondary Switch Contact Protection”, theentire contents of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention generally relates to ground fault circuitinterrupter (GFCI) devices. More particularly, the invention relates toa GFCI device that isolates the face terminals from the load side andprevents an initial miswiring of the GFCI from the load side.

BACKGROUND OF THE INVENTION

GFCI devices are designed to trip in response to the detection of aground fault condition at an AC load. Generally, the ground faultcondition results when a person comes into contact with the line side ofthe AC load and an earth ground at the same time, which is a situationthat can result in serious injury. The GFCI device detects thiscondition by using a sensing transformer to detect an imbalance betweenthe currents flowing in the line and neutral conductors of the ACsupply, as will occur when some of the current on the line side is beingdiverted to ground. When such an imbalance is detected, a solenoidactivates a latched circuit breaker within the GFCI device to an opencondition, thereby opening both sides of the AC line and removing allpower from the load.

Some GFCIs include a lockout feature that prevents the GFCI fromoperating if the solenoid fails to operate. For example, in U.S. Pat.No. 6,381,112 to DiSalvo, which is incorporated by reference herein, aGFCI is provided with a permanent lockout feature which prevents theGFCI from being reset if the solenoid fails to operate or if an openneutral condition exists. However, having a permanent lockout, whichprevents the GFCI from operating, can be undesirable. For example, if ahomeowner is entertaining guests in the kitchen, a power interrupt canoccur requiring the GFCIs to be reset. If a GFCI connected to anappliance is locked out, the homeowner may have to use an extension cordto connect an appliance to a non-GFCI receptacle. In front of guests,this can prove to be embarrassing and inconvenient to the homeowner.

GFCIs can also include an LED to provide a trip indication as disclosedin U.S. Pat. No. 4,568,997, to Bienwald et al., the contents of whichare incorporated herein by reference herein, This type of receptacleincludes test and reset pushbuttons and a lamp or light-emitting diode(LED) which indicates that the circuit is operating normally. When aground fault occurs in the protected circuit, or when the test button isdepressed, the GFCI device trips and an internal circuit breaker opensboth sides of the AC line. The tripping of the circuit breaker causesthe reset button to pop out and the LED to be extinguished, providing avisual indication that a ground fault has occurred. In order to resetthe GFCI device, the reset button is depressed in order to close andlatch the circuit breaker, and this also causes the LED to illuminateonce again. However, the GFCI disclosed in the Bienwald et al. patentdoes not provide an indication of a defective solenoid.

In addition to ground fault detection/protection, protection for thereceptacle terminals of the GFCI is also needed. Specifically, theconventional GFCI device has a set of load terminals that are sharedwith the receptacle terminals leading to the face of the GFCI.Typically, the AC source is connected to the line terminals while thedownstream load devices are connected to the load terminals. However, ifthe GFCI is miswired, this poses a problem. When the load terminals areconnected to an AC source, the receptacle terminals are powered. Theinstaller would be under the impression that the GFCI was operatingcorrectly. However, the installer would be unaware that the GFCI is notproviding ground fault protection even when a fault condition isdetected. Thus, while tripping the latching mechanism in response to amiswiring condition, only the downstream devices are open. Devicesplugged into the GFCI receptacle are still connected to AC power sincethe face terminals are directly connected to the line/load terminals.

It is therefore desirable to provide a latching mechanism that does notshare the contacts between the receptacle terminals and the loadterminals.

It is also desirable to provide a protection device that is notpermanently disabled when the solenoid fails.

It is also desirable to provide a protection device that providesprotection from miswiring, and permanently disables a miswiringprevention device once the protection device is correctly wired.

SUMMARY OF THE INVENTION

The above and other objectives are substantially achieved by a systemand method employing a ground fault circuit interrupter (GFCI) inaccordance with the principles of the present invention.

According to an embodiment of the present invention, an apparatus andmethod for preventing the miswiring of a protection device is employed.The protection device includes line terminals and load terminals. Theprotection device further includes a latching mechanism, adapted to movebetween a closed state which establishes electrical contact between saidline and load terminals, and an open state which prevents electricalcontact between said line and load terminals; and an initial resetprevention mechanism, adapted to prevent said latching mechanism frombeing set in said closed state until power is applied to said lineterminals.

According to another embodiment of the present invention, a protectivedevice having source and load terminals between a conductive path andface terminals is provided. The protective device includes a latchingmechanism, adapted to be operable between a first state in which saidlatching mechanism permits electrical contact between said source loadterminals and said load terminals and a second state in which saidcontact is broken; and a sensing circuit, adapted to selectively placethe latching mechanism in said second state upon detection of a groundfault condition to electrically isolate said face terminals from saidsource and load terminals, a device is connected between hot and neutralconductors of an AC line.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of an example of a ground fault circuitinterrupting (GFCI) device in accordance with an embodiment of thepresent invention;

FIG. 2 is another perspective view of the ground fault interruptingdevice shown in FIG. 1 in accordance with an embodiment of the presentinvention;

FIG. 3 is a perspective view of an example of the ground fault circuitinterrupting device shown in FIG. 1 having an indicator in accordancewith an embodiment of the present invention;

FIG. 4 is a schematic diagram illustrating an example of the circuitryof the ground fault circuit interrupting device of FIG. 1 in accordancewith an embodiment of the present invention;

FIGS. 5-7 are perspective views illustrating examples of positions of alocking plate of the ground fault circuit interrupting device shown inFIG. 1 in accordance with an embodiment of the present invention;

FIGS. 8-10 are cross sectional views illustrating examples of positionsof the locking plate, a latching plate and a reset pin of the groundfault circuit interrupting device of FIG. 1 in accordance with anembodiment of the present invention;

FIG. 11 is a schematic diagram illustrating an example of the circuitryof ground fault circuit interrupting device of FIG. 3 in accordance withan embodiment of the present invention;

FIG. 12 is a schematic diagram of an example of a ground fault circuitinterrupting (GFCI) device in accordance with another embodiment of thepresent invention;

FIG. 13-16 are views illustrating examples of positions of a lockingplate in the GFCI of FIG. 12 in accordance with an embodiment of thepresent invention;

FIGS. 17A and 17B are cross sectional views illustrating examples ofpositions of a initial reset prevention arrangement that can be usedwith a GFCI in accordance with an embodiment of the present invention;and

FIGS. 18A and 18B are cross sectional views illustrating examples ofpositions of a another initial reset prevention arrangement that can beused with a GFCI in accordance with an embodiment of the presentinvention.

FIGS. 19-26 are diagrams showing various positions of switch contactsfor the circuit of FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a perspective view of an example of a ground fault circuitinterrupting (GFCI) device 10 in accordance with an embodiment of thepresent invention. The GFCI device 10 comprises a housing 12 having acover portion 14 and a rear portion 16. The GFCI also includes an innerhousing 13 (See FIG. 5) when the cover portion 14 is removed from therear portion 16. The cover portion 14 and rear portion are removablysecured to each other via fastening means such as clips, screws,brackets, tabs and the like. The cover portion includes plugin slots(also known as face receptacles) 18 and 20 and grounding slots 22. Itwill be appreciated by those skilled in the art that plugin slots 18 and20 and grounding slots 22 can accommodate polarized, non-polarized,grounded or non-grounded blades of a male plug. The male plug can be atwo wire or three wire plug without departing from the scope of thepresent invention. The GFCI receptacle 10 further includes mountingstrap 24 having mounting holes 26 for mounting the GFCI receptacle 10 toa junction box (not shown). At the rear wall of the housing 12 is agrounding screw 28 for connecting a ground conductor (not shown).

A test button 30 extends through opening 32 in the cover portion 14 ofthe housing 12. The test button is used to activate a test operation,that tests the operation of the circuit interrupting portion disposed inthe GFCI receptacle 10. The circuit interrupting portion, to bedescribed in more detail below, is used to break electrical continuityin one or conductive paths between the line and load side of the GFCIreceptacle 10. A reset button 34 extends through opening 36 in the coverportion 14 of the housing 12. The reset button 34 is used to activate areset operation, which reestablishes electrical continuity in the openconductive paths.

Rear portion 16 has four screws, only two of which are shown in FIG. 1.Load terminal screw 38 is connected to a neutral conductor and anopposing load terminal screw 37 (See FIG. 2) is connected to the hotconductor. Line terminal screw 40 is connected to the neutral conductorand an opposing line terminal screw 39 (See FIG. 2) is connected to thehot conductor. It will be appreciated by those skilled in the art thatthe GFCI receptacle 10 can also include apertures proximate the line andload terminal screws 37, 38, 39 and 40 to receive the bare end ofconductors rather than connecting the bare end of the wires to the lineand load terminal screws.

In an embodiment of the present invention rear portion 16 also containsan aperture 42 (See FIG. 2) for accessing the internal portion of theGFCI receptacle 10 for testing during the manufacturing process.Specifically, the aperture 42 provides access to a locking plate 58. Theaperture 42 is sealed prior to shipping of the GFCI receptacle 10 todistributors.

FIG. 3 is a perspective view of an example of a ground fault circuitinterrupting (GFCI) device 11 having an indicator in accordance with anembodiment of the present invention. Specifically, GFCI device 11 issimilar in operation to the GFCI 10 except GFCI device 11 has an alarmindicator 44 for providing an indication to a user that GFCI device 11is not providing ground fault protection, or in other words, GFCI device11 is operating as a normal receptacle.

Alarm indicator 44 comprises a dual color lamp which provides a firstcolor when a first filament is activated and a second color when asecond filament is activated. In an embodiment of the present invention,the alarm indicator 44 illuminates to provide a green color when theGFCI receptacle 11 is operating normally and providing GFCI protection.In another embodiment of the present invention, the alarm indicator 44illuminates to provide a flashing red color when the GFCI receptacle 11is operating as a normal receptacle and not providing ground faultprotection. It should be appreciated by those skilled in the art thatalthough the alarm indicator is described as being a dual filament lamp,two separate single filament lamps, a single lamp having a singlefilament, or a buzzer, or any other suitable indicator such as a coloredlamp can be used to provide an alarm indication without departing fromthe scope of the present invention.

FIG. 4 is a schematic diagram illustrating an example of the circuitryof the ground fault circuit interrupting device of FIG. 1 in accordancewith an embodiment of the present invention. In accordance with thisembodiment, the GFCI device 10 is provided with a latching mechanism 46,sensing circuit 48, solenoid 50, solenoid plunger 52, latching plate 54(See FIG. 8), reset pin 56 (See FIG. 8), locking plate 58, lockingspring 60, secondary contacts 62, neutral conductor 64, hot conductor66, a transformer arrangement 68 comprising sensing transformer 68A andground transformer 68B, and a control circuit 70.

GFCI device 10 is structured and arranged to prevent an initialmiswiring of the GFCI. That is, as described in more detail below, priorto shipping the device for use, the locking plate 58 is pressed downwardto engage a projection on the back of plunger 52 and makes contact withsecondary contacts 62 to thus close the secondary contacts 62. The resetbutton 34, when depressed, cannot engage with the latching plate 54 viathe reset pin 56 and through aperture 55 (See FIGS. 8-10) in thelatching plate 54. When the GFCI receptacle 10 is connected to the lineside, the secondary contacts power the solenoid 50, causing solenoidplunger 52 to release locking plate 58 and position latching plate 54 sothat the reset pin 56 can engage with the edge of the latching plate 54forming the opening 55 when the reset button 34 is depressed.

FIGS. 5-7 are perspective views illustrating examples of positions ofthe locking plate 54 in accordance with an embodiment of the presentinvention. In FIG. 5 the cover portion 14 of the housing 12 is removedto expose the internal housing 13 of the GFCI 10. The locking spring 60,secondary contacts 62, solenoid plunger 52 and solenoid 50 are shown.The locking spring 60 is in an extended or release position and is notexerting pressure.

In FIG. 6, the locking plate 58 is shown in a released or extendedposition. The locking spring 60 (See FIG. 5) holds the locking plate 58up, thus preventing aperture 59 of the locking plate 58 from engagingwith the projection 53 of the plunger 52 or from making contact with thesecondary contacts 62 and closing the secondary contacts 62.

In FIG. 7, the locking plate 58 is shown as being in the down positionand engaged with the projection 53 on the plunger 52 and, thus closingthe secondary contacts 62. That is, an aperture 59 in the locking plate58 interlocks with the projection 53 on the plunger 52 and holds thelocking plate 58 in a position in which the locking plate 58 makescontact with and closes the secondary contacts 62. When the reset button34 is depressed and the locking plate 58 is in a locked state, the resetpin 56 cannot engage with the latching plate 54 because the plunger 52positions the latching plate 54 such that the reset pin 56 passesthrough opening 55 freely. The locking plate 58 will remain in thisposition until the GFCI receptacle 10 is powered from the line side. Ascan be appreciated from the schematic in FIG. 4, the load terminals 37and 38 are electrically isolated from the remainder of the circuit whenthe latching mechanism 46 is in the open state as shown in FIG. 4.However, as is also shown, the secondary contacts 62, when closed by thelocking plate 58, provide a path which enables the solenoid to bepowered from the power source connected to the line terminals 39 and 40and move the plunger 52 in the direction of “A”, thereby removing theprojection 53 of the plunger 52 from the aperture 59 and releasing thelocking plate 58. Accordingly, the spring 60 raises the locking plate 58upward and out of contact with secondary contacts 62, thus opening thesecondary contacts 62.

FIGS. 8-10 are cross sectional views illustrating examples of positionsof the locking plate 58, a latching plate 54 and a reset pin 56 inaccordance with an embodiment of the present invention. In FIG. 8, thelocking plate 58 is shown as being engaged with the projection 53 of theplunger 52 via the aperture 59. The locking plate 58 makes contact withsecondary contacts 62, thus closing them. Locking spring 60 iscompressed and exerts pressure against the locking plate 58, but cannotmove locking plate 58 upwards because locking plate 58 is held in placeby projection 53. In addition, latching plate 54 is positioned toprevent the reset pin 56 from engaging with the latching plate 54. Thatis, the latching plate 54 is positioned to allow the reset pin 56 tofreely pass through the latching plate 54 when the reset button isdepressed without engaging with the latch plate 54.

In FIG. 9, the GFCI receptacle 10 is powered from the line side. Thesecondary contacts 62 which are closed, power the solenoid 50, whichdrives the plunger 52 forward in the direction of “A”. This releases theprojection of the plunger 52 from the aperture 59, and also pushes theplunger 52 against the latching plate 54 to position the opening 53slightly out of alignment with the reset pin 56. The locking spring 60urges the locking plate 58 upward, thus forcing the locking plate intoan extended or non-contacting position. The secondary contacts 62 openand remove power from the solenoid 50.

As shown in FIG. 10, the GFCI receptacle 10 is in a state of normaloperation. That is, the locking plate 58 and locking spring 60 are in anextended position, the secondary contacts are open, and the reset pin 56is able to engage with the edges of the latch plate 54 forming theaperture 53, thus allowing the upper shoulder 57 of the reset pin 56 tocontact and thus engage with the underside of latching plate 54 when thereset button is depressed. Although not shown specifically, the spring60 can thus urge the reset button upward along arrow “UP”, thus drawingthe latch plate 54 and latch block 63 upward. The latch block 63 thuscloses the contacts of latching mechanism 46 to thus provide electricalconnection between the line terminals 39 and 40, and their respectiveload terminals 37 and 38 and face terminals “hot face” and “neutralface”.

Referring now to FIG. 1 and the operation of the GFCI receptacle 10 in aground fault state. The GFCI receptacle 10 is disabled upon detection ofa current imbalance. Specifically, the sensing circuit 48 selectivelyplaces the solenoid 50 in a ground fault state in response to animbalance of current flow in the AC receptacle. While the solenoid 50 isshown here as being a solenoid, other devices such as piezoelectriccomponents and micro electro-mechanical systems (MEMS) may be used. Itcan also be seen that the latching mechanism 46 is connected to thesensing circuit 48 and is placed in series with a plurality ofconductive paths between opposing terminals of the receptacle.Specifically, the latching mechanism 46 breaks a plurality of conductivepaths leading from side line terminals 39 and 40 to side load terminals37 and 38 of the GFCI device 10 when the solenoid 16 is placed in theground fault state.

The latching mechanism 46 is structured such that plugins 18 and 20, theface receptacles, are isolated from the line terminals 39 and 40 and theload terminals 37 and 38. Thus if the GFCI 10 is miswired and/or in atripped position, plugins 18 and 20 will not be powered. A detaileddescription of the operation of latching mechanism 46 can be found inU.S. Provisional Patent Application Ser. No. 60/378,647, referencedabove. Latching mechanism 46 provides improved safety while maintaininga relatively low level of complexity with regard to conventionalapproaches. The latching mechanism 46 has an internal structure thatbreaks the conductive paths between the side A terminals and the side Bterminals and also disconnects a face receptacle hot terminal 256 and aface receptacle neutral terminal 258 from the conductive paths.Specifically, the face receptacle hot terminal 256 is connected to afifth switch contact 234 and the face receptacle neutral terminal 258 isconnected to a first switch contact 226. Both switch contacts 226 and234 are selectively placed in the conductive paths. Thus, by selectivelyplacing the switch contacts 226 and 234 in the conductive paths, theface hot terminal 256 and face neutral terminal 258 can be isolated fromthe conductive paths as well as the side A and B terminals 39 and 40 and37 and 38 when a current imbalance is detected. The latching mechanism46 thus provides improved safety while maintaining a relatively lowlevel of complexity with regard to conventional approaches. The state ofswitch contacts 222, 224, 225, 230, 232 and 233 as shown in FIG. 4indicates that the solenoid 50 has entered the ground fault state, dueto depression of the test button or due to an actual ground fault.However, when the solenoid 50 is not in the ground fault state and thelatching mechanism has been properly reset so that second switch contact222 and third and fourth dual-switch contacts 224, 225 are closed tofirst switch contact 226, and sixth switch contact 230 and seventh andeighth dual-switch contacts 232, 233 are closed to fifth switch contact234; the first conductive path includes the first side A terminal 40,first side A conductor 64, first switch contact 226, second switchcontact 222, third and fourth dual-switch contacts 224, 225, faceterminal receptacle neutral 258, and first side B terminal 38.Similarly, the second conductive path includes second side A terminal39, a second side A conductor 66, fifth switch contact 234, sixth switchcontact 230, seventh and eighth dual-switch contacts 232, 233, faceterminal receptacle hot 256, and second side B terminal 37. While thefirst and second conductive paths are shown as corresponding to theneutral and hot connections respectively, it will be appreciated thatthese assignments can readily be reversed without departing from thescope of the present invention.

It can further be seen that the latching mechanism 46 is structured suchthat, in response to a reset button 34 (see FIG. 19) being pressed onthe AC receptacle, second switch contact 222 comes into contact withfourth switch contact 225. The upward movement of second switch contact222 provides for the second switch contact 222 and third and fourthdual-switch contacts 224, 225 making contact with first switch contact226. Similarly, the sixth switch contact's 230 upward movement providesfor sixth switch contact 230 coming into contact with eighth switchcontact 233. The upward movement is continued until the sixth switchcontact 230 and seventh and eighth dual-switch contacts 232, 233 makecontact with fifth switch contact 234. Thus, face receptacle hot andface receptacle neutral terminals 256 and 258 are connected with theconductive paths and can provide power to a load that is plugged intothe receptacles.

Turning now to FIGS. 19-26 which are diagrams showing various positionsof switch contacts for the circuit of FIG. 4 in accordance with analternative embodiment of the present invention. In FIG. 19, the resetbutton 34, which in an embodiment of the invention is spring loaded, isin an open position. FIG. 20 which shows the GFCI from a different angledepicts first switch contact 226, second switch contact 222, and thirdand fourth dual-switch contacts 224, 225 being open with respect to eachother. FIG. 21 shows the reset button 34 in a closed position while FIG.22 shows first switch contact 226, second switch contact 222, and thirdand fourth dual-switch contacts 224, 225 still being open with respectto each other. As shown in FIG. 23, as the reset button 34 moves backtowards an open position, second switch contact 222 moves upward andcomes into contact with fourth switch contact 225 (see FIG. 24). Whenthe reset button 34 goes back into the open position (see FIG. 25),second switch contact 222 and third and fourth dual-switch contacts 224,225 close with first switch contact 226. Although not shown in thedrawings, the same sequence of events occur for fifth switch contact234, sixth switch contact 230, and seventh and eighth dual-switchcontacts 232, 233.

It should be noted that the sensing circuit 48 effectively defines animbalance of current flow as any difference in the amount of currentflowing in the candidate paths that rises above a predeterminedthreshold.

To better demonstrate the operation of latching mechanism 46, thesensing circuit 48 will now be described in greater detail. Generally,it can be seen that the sensing circuit 48 has a transformer arrangement68, a control circuit 70 and a test switch 30. The transformerarrangement 68 generates control signals in response to the imbalance ofcurrent flow, while the control circuit 70 is connected to thetransformer arrangement 68 and selectively generates a switching signalbased on the control signals. The test switch 30 is connected betweenthe line terminal 40 and the load terminal 37 such that the test switch30 enables manual generation of the imbalance of current flow.

Specifically, when the test switch 30 is closed (for example, manually,by an installer of the device), a circuit path is created from the loadterminal 38 to the line terminal 40, which creates an imbalance that isdetected by a first (or sense) transformer 68A. In an embodiment of theinvention, the first transformer 68A detects imbalances in the net fluxon the load side e.g. terminals 37 and 38 of the GFCI receptacle 10, andoperates in conjunction with the control circuit 70 to energize thesolenoid 50.

Detection of the imbalance condition by the first transformer 68A andthe control circuit 70 causes activation of the solenoid 50 such thatthe latching mechanism 46 is open as shown in FIG. 1. It can be furtherbe seen that a second (grounded neutral) transformer 68B is alsoprovided to allow the transformer arrangement 68 to measure the changein net flux between the first conductive path 64 and the secondconductive path 66.

It can be seen that the control circuit 70 preferably includes anamplifier and trip circuit 72, a full-wave bridge rectifier 74 and asilicon controlled rectifier (SCR) 76. The amplifier and trip circuit 72generate the switching signal, where the bridge rectifier 74 isconnected to the line side terminals 39 and 40. It can be seen that thebridge rectifier 74 provides power to the amplifier and trip circuit 72and that the SCR 76 selectively energizes the solenoid 50 based on theswitching signal. The control circuit 70 preferably includes thecomponents listed in the following table:

CAPACITOR C1 10 MIC OF AND, 16 VDC ALUM, ELECTROLYTIC CAPACITOR C2 3.3MIC, 16 VDC ALUM, ELECTROLYTIC CAPACITOR C3 .01 MIC, 50 VDC CERAMICCAPACITOR C4 .033 MIC, 25 VDC CERAMIC CAPACITOR C5 .01 MIC, 500 VDCCERAMIC CAPACITOR C6 .01 MIC, 50 VDC CERAMIC CAPACITOR C7 470 PIC, 50VDC CERAMIC DIODE D1 IN4004 DIODE D2 IN4004 DIODE D3 IN4004 DIODE D4IN4004 DIODE D5 IN4004 RESISTOR R1 15K OHM, ¼ W CARBON FILM RESISTOR R21.5 MED OHM, ¼ W METAL FILM RESISTOR R3 24K OHM, ½ W CARBON FILMRESISTOR R4 200 OHM, ¼ W CARBON FILM IC RV4145

The state of the latching mechanism 46 as shown in FIG. 4 indicates thatthe solenoid 50 has entered the ground fault state, due to depression ofthe test button 30 or due to an actual ground fault. However, when thesolenoid 50 is not in the ground fault state and the latching mechanism46 has been properly reset so that latching mechanism 46 is closed afirst and second path is created connecting the line terminals 39 and 40to the load terminals 37 and 38 providing power to a load when the GFCI10 is powered from the line side.

It is also important to note that when in the ground fault state, asshown in FIG. 1, an alternative current path is provided between theload terminal 37 and the line terminal 40. Thus, if the AC source isconnected to the line side of GFCI receptacle 10 and the test switch 30is closed, current flows from line side terminal 40, through resistorR1, to the load terminal 37. Thus, this current path will create animbalance in the transformer arrangement 68 resulting in the latchingmechanism 46 being open.

FIG. 11 is a schematic diagram illustrating an example of the groundfault circuit interrupting device of FIG. 13 in accordance with anotherembodiment of the present invention. The GFCI receptacle 11 is similarin operation to the GFCI device 10 discussed above except GFCIreceptacle 11 includes an alarm indicator 44, a test switch 30 havingprimary contacts TS1 and secondary contacts TS2. A detailed descriptionof the operation of the test switch can be found in U.S. patentapplication Ser. No. 10/032,064, filed on Dec. 31, 2001 entitled “GroundFault Circuit Interrupter (GFCI) With A Secondary Switch ContactProtection”, which is incorporated herein by reference.

When test switch 30 is pressed and closes primary test switch contactsTS1, an imbalance is created. The latching mechanism 46 opens and thealarm indicator 44 is extinguished and no longer provides a greencolored illumination. Since the latching mechanism 46 is open, thesubsequent closing of secondary test switch contacts TS2 by test switch30 has no affect on GFCI 11.

In contrast, if the closing of primary test switch contacts TS1 fails totrip the latching mechanism 46, secondary test switch contact TS2 causesa short circuit blowing the fuse F10 and extinguishing the alarmindicator 44 providing green illumination. However, the alarm indicator44 illuminates red. Diode DC10, resistor R11 and capacitor together actto flash alarm indicator 44. The flashing alarm indicator 44 indicatesto a user that GFCI 11 is not providing ground fault protection and isonly operating as an unprotected receptacle and not as a GFCI. Alarmindicator 44 will only flash red when the latching mechanism fails totrip. Thus, the alarm indicator can also serve to provide an indicationof a defective solenoid 50, or any other component of the GFCI that aidsin tripping the latching mechanism 46.

FIG. 12 is a perspective view of an example of a ground fault circuitinterrupting (GFCI) device in accordance with another embodiment of thepresent invention. The GFCI 115 does not contain isolated face terminalsand performs ground fault detection in a manner known to those skilledin the art and will be discussed with reference to its novelty. The GFCI115 includes latching plate 153 (See FIG. 13), secondary contacts 162and a locking plate 157. Latching plate 153 is structured and arrangedso that a portion of the latching plate passes through a plunger end 151(See FIG. 13). The portion of the latching plate 153 passing through theplunger end 151 has a curved end. The curved end of the latching plate153 allows the plunger end 151 to move the latching plate 153 laterallyin the direction of “A” and “B”. Proximate its center, latching plate153 has an aperture 154 to allow reset pin 156 to engage with thelatching plate 153 when the reset button 134 is depressed. In a resetprevention state, the latching plate 153 is positioned such that thereset pin 156 freely passes through the latching plate 153.

Locking plate 157 is used to place the GFCI 115 in a reset preventionstate. The locking plate can be a pin type device, which is insertedthrough the aperture 142 during the manufacturing process between theplunger 151 and the secondary contacts 162, thus closing the secondarycontacts 162. When the GFCI 115 is powered from the load side, there isno power to the solenoid 150. Therefore, the GFCI 115 remains in a resetprevention state because upper shoulder 149 of the reset pin 156 cannotlatch with the bottom surface of the latching plate 153 and reset theGFCI 115. When the GFCI 115 is powered from the line side, the solenoidis powered and moves the plunger in the direction of “B” slightlymisaligning the aperture 154 in the latching plate 153 with the resetpin 156, thus allowing the upper shoulder 149 of reset pin 156 tocontact the lower surface of latching plate 153, and thus pull latchplate 153 and latch block 159 upward to close the contacts of latchingmechanism 178 in a manner similar to that discussed with regard to latchplate 54 and latch block 63. The locking plate 157 falls and opens thesecondary contacts 162, removing power from the solenoid 150.

This embodiment of the invention will now be discussed with reference toFIG. 13-16 which are views illustrating examples of positions of alocking plate in the GFCI of FIG. 12 in accordance with an embodiment ofthe present invention. In FIG. 13, secondary contacts 162 are open andthe locking plate 157 is being inserted into the GFCI 115 via theaperture 142.

In FIG. 14, the locking plate 157 comprising a pin type device isinserted between the plunger 151 and the secondary contacts 162, thusclosing the secondary contacts 162 and allowing the secondary contacts162 to power the solenoid 150 if the GFCI 115 is wired from the lineside. The latching plate 153, however, is positioned to allow the resetpin 156 to freely pass through the aperture 154 and thus not engage withthe latching plate 153 unless the GFCI 115 is connected to the line sidein a manner similar to that discussed above with regard to FIGS. 4-10.

In FIG. 15, the GFCI 115 has been wired to the line side and the plunger151 moves in the direction of “B” to release the locking plate 157. INFIG. 16, the plunger 151 moves in the direction of “A” allowing anaperture in the latch plate 153 to be slightly misaligned with the resetpin 156 as shown in FIG. 16.

FIGS. 17A and 17B are cross sectional views illustrating examples ofpositions of an initial reset prevention arrangement that can be usedwith a GFCI in accordance with another embodiment of the presentinvention. For conciseness, the details of the reset button, and resetpin are not repeated here. In FIG. 17, the locking plate 182 comprises avertical member 182A connected to a horizontal member 182B proximate thecenter of the horizontal member 182B. A locking spring 180 is disposedbetween a portion of the inner housing 113 and an end of the horizontalmember 182B. The locking spring 180 exerts force on the horizontalmember 182B in the direction of “C”. An opposing end of the horizontalmember 182B makes contact with secondary contacts 178 in order to closethe secondary contacts 178. The locking plate 182 is shown in anon-initial reset prevention state. That is, the plunger end 151 doesnot retain the vertical member 182A of the locking plate 182 in aposition in which the horizontal member 182B closes the secondarycontacts 178 by making contact with the secondary contacts 178.

Referring now to FIG. 17B, the plunger end 151 is shown retaining thevertical member 182A of the locking plate 182 which enables thehorizontal member 182B to close the secondary contacts 178. The latchplate 153 is positioned so that the end of the reset pin (not shown) canfreely pass through the opening 154 as discussed above, to preventresetting. As also discussed above, the locking spring 180 is compressedby an end of the vertical member 182 which exerts force in the directionof “C”. When the GFCI is powered from the line side, the secondarycontacts 178 power the solenoid 150 which results in the plunger 151moving in the direction of “A”, thus releasing the locking plate 182.Substantially simultaneously, the spring 180 exerts force on thehorizontal member 182B to propel the horizontal member 182B in thedirection of “C” and open the secondary contacts 178.

FIGS. 18A and 18B are cross sectional views illustrating examples ofpositions of a another initial reset prevention arrangement that can beused with a GFCI in accordance with an embodiment of the presentinvention. Referring to 18B, the solenoid 150 includes a plunger 184having a vertical member 184A, a horizontal member 184B and an aperture184C The vertical member 184A is connected to the solenoid 150 and to alatching plate 186, which is similar to latching plate 153 discussedabove. The horizontal member 184B is connected to the vertical member184A. In an initial reset prevention state, the pin 191 of locking plate190 is aligned with and passes through aperture 184C engages with theupper surface of horizontal member 184B, and thus closes the secondarycontacts 192. In this position, an aperture 187 in the latching plate186 is substantially aligned with a reset pin (not shown) to thus allowthe reset pin to pass through the aperture 187. Thus, the reset pincannot latch with the latching plate 186 and close the latchingmechanism (not shown) to reset: The locking spring 188 is compressed andexerts force on the locking plate 190 in the direction of “C”. However,the locking spring 188 cannot pull the locking plate 190 out of theaperture 184C unless the GFCI is powered from the line side.

Referring now to FIG. 18A, the GFCI has been wired to the line side. Thesecondary contacts 192 power the solenoid 150 moving the plunger 184 inthe direction of “B”. This movement releases the locking plate fromaperture 184C The locking spring 180 propels the locking plate 190 awayfrom the aperture 184C and secondary contacts 192 to a position of restas shown. The release of the locking plate 190 moves the latching plate186 to slightly misalign the aperture 187 in the latching plate 186 withthe reset pin. Thus, the reset pin can engage the latching plate 186 andreset the contacts to a closed state in a manner similar to thatdiscussed above.

Those skilled in the art can now appreciate from the foregoingdescription that the broad teachings of the present invention can beimplemented in a variety of forms. Therefore, while this invention canbe described in connection with particular examples thereof, the truescope of the invention should not be so limited since othermodifications will become apparent to the skilled practitioner upon astudy of the drawings, specification and following claims.

1. An electrical protection device comprising: a phase line terminal; aphase load terminal; a phase face terminal; a neutral line terminal; aneutral load terminal; a neutral face terminal; a phase switch assemblyhaving first and second phase switch contacts and a third phase switchcontact disposed between said first and second phase switch contacts,wherein said first, second and third phase switch contacts are alignedin a single axis and electrically isolated when the electricalprotection device is in a tripped state; a neutral switch assemblyhaving first and second neutral switch contacts and a third neutralswitch contact disposed between said first and second neutral switchcontacts, wherein said first, second and third neutral switch contactsare aligned in a single axis and electrically isolated when theelectrical protection device is in the tripped state; a reset deviceincluding a reset button and a reset pin; and a latch plate, beingmovable by the reset pin when the reset device is actuated such that thefirst, second and third phase switch contacts contact each other and thefirst, second and third neutral switch contacts contact each other toplace the electrical protection device into a reset state.
 2. Theelectrical protection device recited in claim 1, wherein said thirdphase switch contact comprises a single conductive body having first andsecond phase contact faces, respectively, contacting said first andsecond phase switch contacts when the electrical protection device is inthe reset state; and said third neutral switch contact comprises asingle conductive body having first and second neutral contact facesrespectively contacting said first and second neutral switch contactswhen the electrical protection device is in the reset state.
 3. Theelectrical protection device recited in claim 1, further comprising areset enable switch electrically connected between said phase lineterminal and said neutral line terminal, said reset enable switch beingnormally closed and opening when AC power is connected between saidphase line terminal and said neutral line terminal.
 4. The electricalprotection device recited in claim 3, wherein said latch plate comprisesa hole through a portion thereof and the reset pin contacts said latchplate adjacent the hole therein and lifts said latch plate to bring thefirst, second and third phase switch contacts into contact with eachother and the first, second and third neutral switch contacts intocontact with each other when the reset device is actuated.
 5. Theelectrical protection device recited in claim 3, wherein said resetenable switch remains closed when AC power is not connected between saidphase line terminal and said neutral line terminal.
 6. The electricalprotection device recited in claim 3, further comprising a solenoidelectrically connected to one or more of said phase line terminal andneutral line terminal, said solenoid being activated when AC power isconnected between said phase line terminal and said neutral lineterminal.
 7. The electrical protection device recited in claim 6,further comprising: a sensor; a phase electrical conductor connectingsaid phase line terminal to said phase load terminal and being disposedthrough said sensor; a neutral electrical conductor connecting saidneutral line terminal to said neutral load terminal and being disposedthrough said sensor; and a sensor bypass conductor connecting said phaseline terminal to said solenoid and bypassing said sensor such that saidsensor bypass conductor does not pass through said sensor.
 8. Anelectrical protection device comprising: a phase line terminal and aphase load terminal; a neutral line terminal and a neutral loadterminal; a phase switch assembly electrically connecting said phaseline terminal and said phase load terminal in a reset state andelectrically isolating said phase line terminal and said phase loadterminal in a tripped state, said phase switch assembly including aphase line member attached to said phase line terminal and having aphase line contact, and a phase load member attached to said phase loadterminal and having a phase load contact aligned with said phase linecontact in a first single axis; a neutral switch assembly electricallyconnecting said neutral line terminal and said neutral load terminal ina reset state and electrically isolating said neutral line terminal andsaid neutral load terminal in a tripped state, said neutral switchassembly including a neutral line member attached to said neutral lineterminal and having a neutral line contact, and a neutral load memberattached to said neutral load terminal and having a neutral load contactaligned with said neutral line contact in a second single axis; a resetdevice including a reset button and a reset pin; a latch plate having anaperture, the reset pin engaging the reset plate adjacent the aperturewhen the reset button is pressed; a latch block engaging said latchplate and causing said phase and neutral switch assemblies to enter thereset state when the reset button is released; and a reset enable devicehaving an open state and a closed state, the latch plate being preventedfrom causing said phase and neutral switch assemblies to remain in thereset state until said reset enable device is in the open state.
 9. Theelectrical protection device recited in claim 8, further comprising: aphase face contact aligned in the first single axis and connected to aphase receptacle, said phase face contact being electrically connectedto said phase line contact and said phase load contact in the resetstate and electrically isolated from said phase line contact and saidphase load contact in the tripped state; and a neutral face contactaligned in the second single axis and connected to a neutral receptacle,said neutral face contact being electrically connected to said neutralline contact and said neutral load contact in the reset state andelectrically isolated from said neutral line contact and said neutralload contact in the tripped state.
 10. The electrical protection devicerecited in claim 8, further comprising: a solenoid electricallyconnected to said phase line terminal; and a plunger actuated to movesaid latch plate when power is applied to said solenoid, power beingapplied to said solenoid when both AC power is applied to said phaseline terminal and said reset enable device is in the closed state. 11.The electrical protection device recited in claim 10, furthercomprising: a sense transformer arranged to detect an imbalance inelectrical current flowing through two or more conductors; a phaseelectrical conductor connecting said phase line terminal and said phaseswitch assembly, said phase electrical conductor traversing through saidsense transformer; a neutral electrical conductor connecting saidneutral line terminal and said neutral switch assembly, said neutralelectrical conductor traversing through said sense transformer; a faultswitch electrically connected to said solenoid and having a conductingstate and a nonconductive state; and a trip circuit activating saidfault switch when said sense transformer detects an imbalance inelectrical current between said phase electrical conductor and saidneutral electrical conductor, power being applied to said solenoid whensaid fault switch is in the conductive state, when AC power is appliedto said phase line terminal and, said reset enable device is in the openstate.
 12. The electrical protection device recited in claim 10, whereinsaid reset enable device comprises a pair of electrical contacts and aconductive switch plate held in contact with the pair of electricalcontacts when AC power is applied to said phase load terminal.
 13. Theelectrical protection device recited in claim 12, wherein said switchplate comprises an aperture and is held in contact with the pair ofelectrical contacts by said plunger engaging the aperture of said switchplate.
 14. The electrical protection device recited in claim 8, whereinwhen said reset enable device is in the closed state, the reset pin isunable to engage the aperture in said latch plate if said reset enabledevice is in the closed state.
 15. The electrical protection devicerecited in claim 8, wherein one of said phase line contact and saidphase load contact comprises a phase dual contact having an electricalcontact surface on each of two opposite sides thereof; and wherein oneof said neutral line contact and said neutral load contact comprises aneutral dual contact having an electrical contact surface on each of twoopposite sides thereof.
 16. An electrical protection device comprising:a phase line terminal and a phase load terminal; a neutral line terminaland a neutral load terminal; a phase switch assembly electricallyconnecting said phase line terminal and said phase load terminal in areset state and electrically disconnecting said phase line terminal andsaid phase load terminal in a tripped state; a neutral switch assemblyelectrically connecting said neutral line terminal and said neutral loadterminal in a reset state and electrically disconnecting said neutralline terminal and said neutral load terminal in a tripped state; asensor; a phase conductor electrically coupled to said phase lineterminal and said phase switch assembly and traversing through saidsensor; a neutral conductor electrically coupled to said neutral lineterminal and said neutral switch assembly and traversing through saidsensor; an enable circuit enabling the electrical protection device toenter the reset state after AC power is attached to one or more of saidphase line terminal and said neutral line terminal, electrical currentnot flowing through said phase conductor through said sensor whenelectrical current is flowing through said enable circuit and AC poweris attached to one or more of said phase line terminal and said neutralline terminal.
 17. The electrical protection device recited in claim 16,further comprising: a detection circuit electrically coupled to saidsensor and generating a detection signal when an imbalance existsbetween an electrical current flowing in said phase conductor and anelectrical current flowing in said neutral conductor, said detectioncircuit not generating the detection signal when electrical currentflows through said enable circuit.
 18. The electrical protection devicerecited in claim 16, wherein one of said phase switch assembly and saidneutral phase assembly includes, a line contact electrically coupled toa respective line terminal; a load contact electrically coupled to arespective load terminal and aligned with said line contact in a firstaxis; and a face contact electrically coupled to a respective facereceptacle and aligned with said line contact and said load contact inthe first axis.
 19. The electrical protection device recited in claim16, wherein said enable circuit comprises at least an actuator and aswitch, said switch permanently open circuiting said enable circuitafter AC power is attached to one or more of said phase line terminaland said neutral line terminal.
 20. The electrical protection devicerecited in claim 19, wherein said actuator opens said switch topermanently open circuit said enable circuit.
 21. The electricalprotection device recited in claim 16, wherein one or more of said phaseswitch assembly and said neutral switch assembly includes, a lineconductor attached to a respective phase or neutral line terminal at afirst thereof and having a line contact attached to a movable second endthereof, a load conductor attached to a respective phase or neutral loadterminal at a first thereof and having a load contact attached to amovable second end thereof, the load contact being aligned in a singleaxis with the line contact, and a face conductor attached to arespective phase or neutral face receptacle and having a face contactattached thereto, the face contact being aligned in the single axis withthe line contact and the load contact.
 22. A GFCI receptacle comprising:phase line, load and face terminals; neutral line, load and faceterminals; a latching mechanism movable between a closed stateestablishing one or more of electrical contact between said phase line,load and face terminals and electrical contact between said neutralline, load and face terminals, and an open state disconnecting one ormore of electrical contact between said phase line, load and faceterminals and disconnecting electrical contact between said neutralline, load and face terminals; the latching mechanism including, a firstswitch assembly being in a phase current path between the phase line andphase load terminals and having a first switch contact, a second switchcontact, and third and fourth dual-switch contacts disposed between saidfirst and second switch contacts for selectively opening or closing thephase current path, the first and second switch contacts and the thirdand fourth dual-switch contacts being aligned in a single axis, and asecond switch assembly being in a neutral current path between theneutral line and neutral load terminals and having a fifth switchcontact, a sixth switch contact, and seventh and eighth dual-switchcontacts disposed between said fifth and sixth switch contacts forselectively opening or closing a second conductive path, the fifth andsixth switch contacts and the seventh and eighth dual-switch contactsbeing aligned in a single axis; and a movable and spring biased resetpin coupled to said latching mechanism and causing the respective switchcontacts to move between open and closed positions.
 23. A GFCIreceptacle as claimed in claim 22, wherein said third and fourthdual-switch contacts comprise a first contact surface oriented along thesingle axis, and a second contact surface oriented in the oppositedirection from said first surface along the single axis.
 24. A GFCIreceptacle as claimed in claim 23, wherein said first and second contactsurfaces are both part of a single unitary conductive contact structureattached to a movable end of a flexible conductive brush arm.
 25. A GFCIreceptacle as claimed in claim 23, wherein the first contact surface ofsaid third and forth dual-switch contacts faces the first switch contactof said first switch assembly and the second contact surface of saidthird and forth dual-switch contacts faces the second switch contact ofsaid first switch assembly.
 26. A ground fault circuit interrupter(GFCI) receptacle comprising: a line terminal; a load terminal; a useraccessible face terminal; a resilient first cantilevered contact armelectrically connected to said line terminal at a fixed end of saidfirst cantilevered contact arm and having a movable line electricalcontact at a free end of said first cantilevered contact arm; aresilient second cantilevered contact arm electrically connected to saidload terminal at a fixed end of said second cantilevered contact arm andhaving a movable load electrical contact at a free end of said secondcantilevered contact arm; a face electrical contact electricallyconnected to said user accessible face terminal, each of said load, lineand face electrical contacts being substantially aligned along a commonaxis, being electrically isolated from each other when the GFCI is in atripped condition and being electrically connected with each other whenthe GFCI is in a reset condition, at least two of said load, line andface electrical contacts being biased toward an electrically isolatedposition; and a movable and spring biased reset pin connected to saidelectrical contacts to move said electrical contacts betweenelectrically isolated and electrically connected positions.
 27. The GFCIreceptacle recited in claim 26, wherein one of the line electricalcontact and the load electrical contact is a dual-sided contact assemblyhaving two contact surfaces located on opposite sides thereof, and theother of the line and load contacts is a single-sided contact having asingle contact surface located on one side of the respective electricalcontact, and a movable latch block coupled to said reset pin engages atleast one of said cantilevered contact arms to move the line electricalcontact, the load electrical contact and the face electrical contactinto electrical contact.
 28. A ground fault circuit interrupter (GFCI)receptacle comprising: a housing; phase and neutral line terminals atleast partially disposed within said housing and connected to a sourceof AC power; phase and neutral load terminals at least partiallydisposed within said housing and connected to a first electrical load;phase and neutral user accessible face terminals at least partiallydisposed within said housing; phase and neutral first flexibleconductive contact arms having first ends being fixedly connected tosaid phase and neutral line terminals, respectively, and second endseach having a respective first electrical contact connected adjacent arespective free end thereof; phase and neutral second flexibleconductive contact arms having first ends being fixedly connected tosaid phase and neutral load terminals, respectively, and the second endseach having a respective second electrical contact adjacent a respectivefree end thereof; phase and neutral face electrical contactselectrically respectively connected to said phase and neutral useraccessible face terminals and aligned substantially along phase andneutral axes with the respective first and second electrical contacts,the first and second contacts being movable along the respective axesbetween first positions in which the respective face, line and loadelectrical contacts are electrically connected and second positions inwhich the respective face, line and load contacts are spaced andelectrically isolated from one another, respective ones of saidelectrical contacts being biased toward said second positions; a resetassembly at least partially disposed within said housing and including aspring biased and movable reset pin; a latch plate engaging at least thereset pin; and a latch block assembly engaging at least one of saidphase and neutral first flexible conductive contact arms and said phaseand neutral second flexible conductive contact arms and said latchplate; whereby when said reset assembly is activated the reset pinengages said latch plate and moves said latch block assembly towardseach of said flexible contact arms such that the phase first electricalcontact and the phase second electrical contact are moved to contact thephase face electrical contact, and the neutral first electrical contactand the neutral second electrical contact are moved to contact theneutral face electrical contact.